The present invention relates to in-vehicle navigation systems and more particularly the present invention relates to using a navigation system interactively to provide guidance about alternative routes while driving.
In-vehicle navigation systems are available that provide end users (such as drivers of the vehicles in which the in-vehicle navigation systems are installed) with various navigating functions and features. For example, some in-vehicle navigation systems are able to determine an optimum route to travel by roads between locations in a geographic region. Using input from the end user, and optionally from equipment that can determine one's physical location (such as a GPS system), a navigation system can examine various routes between two locations to determine an optimum route to travel from a starting location to a destination location in a geographic region. The navigation system may then provide the end user with information about the optimum route in the form of instructions that identify the driving maneuvers required to be taken by the end user to travel from the starting location to the destination location. The instructions may take the form of visual and/or audio instructions that are provided along the way as the end user is traveling the route. Some navigation systems are able to show detailed maps on computer displays outlining routes to destinations, the types of maneuvers to be taken at various locations along the routes, locations of certain types of features, and so on.
In order to provide these and other navigating functions, navigation systems use geographic data The geographic data may be in the form of one or more databases that include data that represent physical features in a geographic region. The geographic database may include data representing the roads and intersections in a geographic region and also may include information relating to the represented roads and intersections in the geographic region, such as turn restrictions at intersections, speed limits along the roads, street names of the various roads, address ranges along the roads, and so on.
Although navigation systems provide many important features, there continues to be room for improvements. One area in which there is room for improvement relates to using a navigation system to provide route guidance that takes into account driving or traffic conditions observed by the vehicle driver. For example, the driver may observe a traffic condition that may have an affect on how quickly a destination is reached. According to one example, the driver may observe that the road ahead along the calculated route is backed up with traffic congestion. According to another example, the driver may observe that a left turn signal in a stop light at an upcoming intersection would allow a left turn to be made sooner than proceeding straight ahead along a calculated route. Under these circumstances, the driver may not be satisfied with staying on the calculated route because conditions that the driver observes may suggest that an alternative route may be faster. However, prior navigation systems have not provided a way to take driver-observable conditions into account.
It is noted that some in-vehicle navigation systems have been proposed that obtain and use real-time traffic information. According to one type of proposed system, data about traffic congestion in a geographic area are collected by a traffic information service. The collected traffic data are filtered and processed. Then, the traffic information service broadcasts messages that contain information about the traffic congestion along roads in the geographic area. The in-navigation systems in the vehicles traveling in the geographic area include equipment that receive the messages. Programming in the in-vehicle navigation systems use the information about traffic congestion when calculating optimal routes and when providing route guidance.
Although these types of proposed systems can be beneficial to vehicle users, these types of systems rely on the collection and broadcasting of traffic congestion information by a traffic information service. Many geographic regions may not have a traffic information service that collects traffic data and broadcasts messages that can be used by in-vehicle navigation systems. Further, even if a traffic information service is available in a geographic area, the traffic information service may collect and broadcast traffic congestion data about only certain roads (e.g., those that have the highest volume of traffic). If the driver of the vehicle with the in-vehicle navigation system is traveling on a road that is not covered by the traffic information service, he/she may not be able to obtain up-to-date traffic information.
Accordingly, there continues to be a need to provide alternative ways to provide navigation assistance to a vehicle driver using a navigation system.